Most biological macromolecules are electrically charged such that, when subjected to an electrical field, they begin to move. This phenomenon is the basis behind an electrophoresis process wherein a prescribed electrical current is generated adjacent to a collection of macromolecules to produce movement of the macromolecules through a solvent in a particular direction. Since different macromolecules vary in molecular weight and charge, it is possible to use an electrophoresis process to distinguish between different macromolecules based on their respective rates of movement through the solvent. Electrophoresis can also be used for other types of macromolecule analyzation, such as detecting amino acid changes, nucleic acid sequencing and protein analysis.
One medium that has been used for over thirty years as the carrier for the macromolecules in an electrophoresis process is a gel, primarily agarose and polyacrylamide gels. An electrophoresis gel is typically planar in shape and includes a series of spaced apart wells. The wells are designed to receive the biological sample being tested. Originally, it was customary for the laboratory doing the testing to cast their own gels by hand. It soon became apparent, however, particularly as electrophoresis testing of DNA increased, that it is more convenient and more precise to use precast gel slabs made to uniform composition, size and well configuration standards.
Conventional gels are made from various materials depending on their intended use. One widely used gel material for DNA electrophoresis is agarose. This gel is a sugar based gel that is highly flimsy and subject to tearing and deformation if not handled carefully. Tearing or cracking is especially prone between the wells where the least amount of material is present. Deformation or tearing of the gel can potentially produce inaccuracies during testing. To complicate matters further, the material properties of the gel make detecting hairline cracks very difficult. Hence, proper packaging of the gels is extremely important when shipping or storing the gels.
Several packaging arrangements have been developed in recent years to protect electrophoresis gels during shipment. U.S. Pat. No. 5,443,704 discloses one packaging arrangement for protecting the gels. This packaging arrangement includes a plastic tub within which the gel is placed. A foil-lined cover is adhered to the top of the tub to retain moisture inside the package. It was subsequently determined that the tub alone did not provide sufficient protection for the gel. Filler materials had to be added to the box to provide adequate protection from damage. This type of packaging arrangement is generally very expensive to produce.
Another prior packaging arrangement for shipping gels includes a pouch formed from foil material that is sealed along each edge. In order to protect the gel, a separate sheet of material is folded over the gel to separate it from the foil. A deficiency with this packaging arrangement is that the package does not adequately protect the gel from damage such as edge deformation and well breakage.
A need, therefore, exists for an improved packaging arrangement which is inexpensive to manufacture and which adequately protects a gel or series of gels from damage during shipment, handling or while stored.